1. Technical Field
The present disclosure relates to registration and, more specifically, to a method and system for deformable 2D-3D registration of structure.
2. Discussion of Related Art
Abdominal aortic aneurysm (AAA) is a localized expansion (i.e. ballooning) of the abdominal aorta. With AAA, there is a risk that the aneurysm may rupture if the expansion becomes large enough. In the event of a rupture, the chances of survival for the patients are low. AAA is among the leading causes of death in the U.S. While AAA is traditionally treated using open surgical repair, in recent years, minimal-invasive interventional have emerged as an alternative to open surgeries for the treatment of AAA. This may be particularly apparent for patients who are at an increased surgical risk due to age or other medical conditions.
During the interventional procedure for the repair of AAA, as with other forms of vascular intervention, X-ray imaging may be used for the guidance and navigation of a catheter and graft within the aorta. For example, fluoroscopy may be used to capture periodic or continuous x-ray images so that the catheter and graft may be visualized during the intervention. As the X-ray imagery tends to lack sufficient visualization of the aorta and other vasculature, radiocontrast may be used to enhance visualization.
However, performing interventions using monoplane fluoroscopic images is difficult both because of the lack of detail and depth. Lack of detail may be particularly problematic where radiocontrast is not used. Use of radiocontrast, however, increases patient exposure to radiation and may in certain situations obstruct visualization of the catheter and graft.
Modern techniques for providing visual guidance during vascular intervention such as endovascular AAA repair may thereby combine pre-operative 3D volumetric data such as an MRI or CT scan with intra-operative 2D X-ray images to provide realistic artery anatomy with minimal or no need for radiocontrast. Moreover, such visual overlays may provide useful information to the physicians for finding the best path and target position.
Combining the pre-operative volumetric data with the intra-operative 2D X-ray data poses special difficulties as the size, shape and relative location of vascular anatomy is subject to change as the patient moves due to body motion, heart beat, breathing and the insertion of medical devices into the artery during AAA procedures.
Approaches have been proposed for the rigid alignment of pre-operative 3D imagery and intra-operative 2D images registration. While such approaches may be robust in the estimation of the general pose, these techniques may be unable to effectively correct for local deformations within the vessel.
While methods for deformable 2D/3D registration have been used, existing approaches may be ill-suited for application to vascular structures due at least in part due to the complex and repetitive structure and the high degree of deformation that may occur.